Structural testing is used to verify the static strength, or fatigue strength of a component by applying measured loads.

Structural Testing

Structural testing is used to verify the static strength, or fatigue strength of a component by applying measured loads. Testing can be done to failure, to contractual requirements or to validate finite element model predictions. DTB has successfully completed thousands of structural tests on items ranging in size and complexity from simple coupons to entire aircraft. Fatigue testing is carried out with the objective of determining the relationship between the stress range and the number of times it can be applied before causing failure.

When you need predictable product structural durability, verified and validated, DTB’s test experts can answer your requirements. We can develop and document your test program, providing certified equipment and personnel to authoritatively assess the design and manufacturing integrity of your product.

Fatigue Testing

DTB has an overly-equipped A2LA accredited test laboratory capable of performing coupon, component and full-scale fatigue testing. Over 100 major test fixtures are available to test specific aircraft components.

We also have the engineering resources and design talent to design and fabricate specialized test fixtures to test any type of component requiring fatigue testing.

  • Our centralized hydraulic power unit supplies 800 GPM of hydraulic fluid at 3,000 psi pressure.
  • DTB performs constant amplitude or spectrum fatigue loading of components up to 200 kips* ** at frequencies up to 25 hertz (depending on load and displacement requirements).
  • We have the capability of applying both linear and angular displacements utilizing linear and rotary hydraulic actuators.
  • Comparison fatigue testing of OEM and alternate source parts can also be performed to demonstrate equivalency of fatigue life.

*That’s nearly 890 kilonewtons!
**What’s a kip? – Combines “kilo” and “pound” 1,000 pounds; aka kilopound.

DTB has extensive facilities and expertise in coupon/mechanical testing, for static as well as constant amplitude and spectrum fatigue testing.

DTB facilities include a static load Tinius Olsen, two Instron test systems and two servo hydraulic MTS systems to perform several type of material, hardware or component tests. The testing ranges can reach up to 120 kips Statically and 22 kips (tension) dynamically.

Our reliable and accurate testing solutions are ideal for advanced materials research, product development, quality control, and manufacturing process optimization. DTB can investigate overload failure, fatigue fracture, tensile fracture and compression buckling while providing total life, crack initiation and crack growth data.

We also provide coupon programs for environmental (high temp and low temp) and corrosion effects on materials as well as surface finishes.

Coupon programs are normally low cost, simple to conduct, tests that permit the evaluation of materials (or variations of materials), hardware or components. Coupon programs can be used for metallurgical variations evaluation (i.e., the effect of heat treatment and microstructure), alloy chemistry variations evaluation and coupon tests can be adapted to evaluate specific types of surface finish, environmental and corrosion conditions.

Static and Dynamic Load Testing - DTB can assist you in any phase of your loads testing program, to determine the actual, real world loading conditions on your system. Using strain gauges, load calibrations, data recording equipment and other instrumentation, the loading history can be recorded and analyzed to satisfy any data requirements you may have.

This information can be used in analytical life predictions and for discrete tests. If further testing is required, based on the results, a static load test or a dynamic load test may be recommended.

In most cases for solid structures, a static load test is recommended while assemblies with relative motion between parts are better suited for dynamic load tests.

Static Load Test - If a static load test appears to be the best option, load cases can be developed to simulate critical conditions. During the static load test, data can be continuously recorded with data “snapshots” taken at prescribed loading increments.

Dimensional inspections can be conducted to quantify any permanent deflections or set either pre-static loading and/or post-static loading.

Dynamic Load Test - If a dynamic load test is recommended, using statistical methods a loading spectrum can be determined that expands the recorded data into the full range of conditions. If you have simulated or recorded field data, we can work with you to “truncate” the spectrum and weed out the conditions that do not affect the component.

The leaner spectrum can expedite testing, thus reducing time and expense. This type of dynamic load testing is similar to fatigue testing with emphasis on the actual loading environment and geometry as opposed to idealized loads on coupon samples.

The resulting data is based less on assumptions and models with part to part interactions bearing on the outcome of the dynamic load test.

Servo-Controlled Load Application — DTB utilizes Servo-Controlled linear or rotary hydraulic actuators to apply the test loads or displacements during all static and fatigue testing.

Load control for fatigue applications is typically accomplished using Cyber computer controlled servo feed back control systems or our new MTS 16-Channel AERO ST Structural Test Controller.

The MTS AERO ST Controller is a reconfigurable load control system that can conduct both static and fatigue test programs using the latest in structural test control software and algorithms.

The Aero ST controller employs industry-standard hardware for easy upgrades and runs on Windows operating system. It has an intuitive graphical user interface, making it easy to set up and run.

The multi-tasking operating system allows you to define new tests, analyze past results and monitor active tests currently in process, all at the same time. Coupled with AeroPro Control and Data Acquisition Software allows the user to access synchronized control and data acquisition information in real-time from a single source.

The servo valves utilized on the hydraulic actuators can be load controlled or displacement controlled dependent on the feed back used. In all cases, the computer software controlling the test loads or displacements are programmed to terminate the test if the parameters shift in excess of five percent of the baseline settings.

These systems developed by DTB have been proven throughout years of performance on both fatigue and static tests performed for military and commercial customers. The Cyber servo-controllers are driven by durable Hewlett-Packard UNIX based computers, which allow for flexibility in programming wave shapes, load spectrums, and static load profiles. These systems are currently capable of 16 control channels and are easily expandable as required.

Instrumentation and Data Acquisition - DTB has the capability of acquiring and recording 100+ strain measurements, 25+ deflection measurements and 30+ load measurements.

This is accomplished with either of two types of data acquisition systems which are Hewlett Packard VXI 75000 Series hardware with HPVEE software or National Instruments SCXI hardware with LabVIEW software or VTI Technology EX1629 Remote Strain Gage Measurement Unit integrated with the MTS 16-channel Aero ST Structural Test Controller.

Our engineers can quickly tailor software programs to meet customer requirements for data recording and realtime display of data.

Hydraulic Pressure Testing - DTB’s powerful in-house hydraulic plant and years of experience building hydraulic pressure systems provides us the capability to handle the most demanding hydraulic pressure tests.

For tests requiring large flow rates, we have several 100 gpm pumps available. We have performed static pressure tests to 30,000 psi and have the capability to do dynamic pressure tests with pressures up to 18,000 psi.

The hydraulic fluids we test with include MIL-H-83282, MIL-H-81722, MIL-H-5606, DTE24 and a range of ROYCO fluids of various compositions. Pressure testing using Skydrol is also available.

If a hydraulic pressure test is required for part certification, we have experience testing to the many hydraulic pressure test standards such as AMS 2620C for proof pressure testing. Impulse testing to ARP 1383 is also possible and in smaller assemblies, we have achieved pressurization rates of 100,000 psi/second.

We have conducted hydrostatic pressure tests on numerous components such as landing gear, coolant manifolds, hydraulic actuators and large shipboard hydraulic components.

Cyclic Hydraulic pressure test can reveal unforeseen stress concentrations around ports and mounting geometry on vessels and fittings. To evaluate these stresses, we can instrument your assembly with strain gauges or we can conduct periodic non-destructive inspections for cracks and track their growth to provide data for life predictions.

If you have a new hydraulic component, DTB has the instrumentation available to provide accurate data to help you build your specification sheet. Characteristics such as flow rate tests and head losses can be measured.

A high and low temperature hydraulic pressure test can be conducted to find the bounds of your component’s operating envelope. Efficiency tests of hydraulic motors and cylinders can be performed as well.